1. Field of the Invention
This invention relates to a cartoning machine which wraps cartons about preformed blocks of objects, such as bottles, cans or other similar containers.
2. Discussion of Related Art
Automatic cartoning machines are known in which the objects to be cartoned arrive from an accumulation conveyor line, and are divided into blocks each formed from a required number of rows and columns of objects, to then proceed as suitably spaced-apart blocks with a continuous movement on a feed line aligned with the accumulation conveyor line, along said feed line there being disposed in succession various operating stations in which the different operations are carried out, namely: inserting a carton under each block, using flat prepunched cartons withdrawn from a store; folding the flaps of the carton so as to wrap it about the block; and folding and glueing the side portions of the carton to finally obtain a closed carton which completely encloses the block of objects and is ready for despatch.
The spaced-apart blocks of objects are fed through the successive operating stations generally initially by means of a chain conveyor with transverse thrust bars disposed at a predetermined pitch, and later by a prong conveyor, with the prongs acting on the tail end of the blocks after they have been partly wrapped by the relative cartons.
In these cartoning machines, certain difficulties are encountered in the station in which the individual cartons are inserted under the individual blocks of objects. This station normally lies at the end of the chain conveyor having the transverse thrust bars. The flat punched carton, withdrawn from the carton store, is urged by suitable thrust members transversely to the block feed line, and before its horizontal part is inserted under the relative block, another part of the carton is folded upwards through 90.degree. so that when the carton is inserted under the block of objects, this vertical folded part of the carton closes the front end of the block (with reference to its feed direction). Under these conditions, the horizontal part of the carton obviously projects rearwards from the block of objects, in the form of the flap which, after being folded, is to close the rear end of the block, and the vertical part of the carton projects upwards from the block, in the form of the flap which after folding is to close the top of the block. The carton which has just been inserted under the block projects from its two sides in the form of side portions which, after folding, laterally close the block of objects.
Now during the insertion of the horizontal part under the block, the vertical part of the carton creates interference difficulties with the block thrust bars, and more precisely with the side chains which support said bars, so that the carton has to be inserted transversely to the feed line at the end of the chain conveyor where this conveyor is deviated upwards, so as to obviate said interference. Furthermore, the horizontal part of the carton, and in particular the rear projection which projects beyond the base of the relative block, requires a considerable increase in the pitch of the chain conveyor thrust bars if interference between the successive cartons inserted under the fed blocks of objects is to be prevented. It is apparent that this circumstance considerably limits the productivity of these known cartoning machines.